/*------------------------------------------------------------------------
*
* geqo_ox2.c
*
*     order crossover [OX] routines;
*     OX2 operator according to Syswerda
*     (The Genetic Algorithms Handbook, ed L Davis)
*
* src/backend/optimizer/geqo/geqo_ox2.c
*
*-------------------------------------------------------------------------
*/

/* contributed by:
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
   *  Martin Utesch                 * Institute of Automatic Control       *
   =                             = University of Mining and Technology =
   *  utesch@aut.tu-freiberg.de  * Freiberg, Germany                   *
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
 */

/* the ox algorithm is adopted from Genitor : */
/*************************************************************/
/*                                                             */
/*    Copyright (c) 1990                                         */
/*    Darrell L. Whitley                                         */
/*    Computer Science Department                                 */
/*    Colorado State University                                 */
/*                                                             */
/*    Permission is hereby granted to copy all or any part of  */
/*    this program for free distribution.   The author's name  */
/*    and this copyright notice must be included in any copy.  */
/*                                                             */
/*************************************************************/

#include "postgres.h"
#include "optimizer/geqo_random.h"
#include "optimizer/geqo_recombination.h"

#if defined(OX2)

/* ox2
 *
 *     position crossover
 */
void
ox2(PlannerInfo *root, Gene *tour1, Gene *tour2, Gene *offspring, int num_gene, City * city_table)
{// #lizard forgives
    int            k,
                j,
                count,
                pos,
                select,
                num_positions;

    /* initialize city table */
    for (k = 1; k <= num_gene; k++)
    {
        city_table[k].used = 0;
        city_table[k - 1].select_list = -1;
    }

    /* determine the number of positions to be inherited from tour1  */
    num_positions = geqo_randint(root, 2 * num_gene / 3, num_gene / 3);

    /* make a list of selected cities */
    for (k = 0; k < num_positions; k++)
    {
        pos = geqo_randint(root, num_gene - 1, 0);
        city_table[pos].select_list = (int) tour1[pos];
        city_table[(int) tour1[pos]].used = 1;    /* mark used */
    }


    count = 0;
    k = 0;

    /* consolidate the select list to adjacent positions */
    while (count < num_positions)
    {
        if (city_table[k].select_list == -1)
        {
            j = k + 1;
            while ((city_table[j].select_list == -1) && (j < num_gene))
                j++;

            city_table[k].select_list = city_table[j].select_list;
            city_table[j].select_list = -1;
            count++;
        }
        else
            count++;
        k++;
    }

    select = 0;

    for (k = 0; k < num_gene; k++)
    {
        if (city_table[(int) tour2[k]].used)
        {
            offspring[k] = (Gene) city_table[select].select_list;
            select++;            /* next city in  the select list   */
        }
        else
            /* city isn't used yet, so inherit from tour2 */
            offspring[k] = tour2[k];
    }

}

#endif                            /* defined(OX2) */
